Relative estimation of the Karhunen-Loève transform basis functions for detection of ventricular ectopic beats

Feasibility of the Karhunen-Loeve transform (KLT)for detection of ventricular ectopic beats was studied. The KLT basis functions of normal QRS complexes were derived for a small-sized training set of heartbeats. The relevant KLT features were obtained by comparison between five selected heartbeats of the predominant rhythm and the remaining heartbeats in the tested electrocardiographic (ECG) recording. Statistical analysis of the KLT features for MIT-BIH arrhythmia database contributed to the definition of threshold criteria for discrimination between the predominant and the ventricular ectopic heartbeats. The achieved accuracy was about 97.7% for single-lead analysis and above 98% for joint two-lead processing. The method is attractive and suitable for implementation in an automatic analysis module because of the necessity for supervisor annotation of only five beats of the predominant rhythm in one ECG recording.